A sub group of dyslexic patients with square wave jerks present during fixation and reading was identified and both reading ability and square wave intrusions were markedly improved with methylphenidate. Directionally cued visual behavior is impaired in the visual field contralateral to parietal lesions in humans, but diffusely cued visual tasks are impaired in both visual fields. Similar deficits are found when lesions are made in area 7 or the lateral pulvinar of the macaque. Pursuit function was studied in patients with parietal and frontal lobe lesions, schizophrenia and Alzheimer's disease, and a comparison was made with slow phase velocity of OKN. The frequency of fixational square wave jerks was also studied in the above patients and also in patients with hypothalamic and chiasmal tumors. Cortical visual loss occurred as a temporary side effect in four patients receiving high dose intravenous chemotherapy for lymphoma or leukemia. Magnetic resonance scanning showed good anatomic correlation, with occipital lobe edema. Positron emission scanning (PET) was used to correlate visual functions with glucose utilization in different anatomical areas of the brain. This included patients with homonymous hemianopias, bilateral optic nerve transection and albinism. The possible contribution of extrageniculostriate pathways to visual processing following lesions of the geniculostraite pathway was studied in patients with lesions of optic chiasm, primary visual cortex or optic radiations.